Yunyao Jiang

Antioxidant properties and neuroprotective effects of isocampneoside II on hydrogen peroxide-induced oxidative injury in PC12 cells

Oxidative stress has been considered as a major cause of cell damage in various neurodegenerative disorders. One of the reasonable strategies for delaying the diseases progression is to prevent reactive oxygen species (ROS) mediated cellular injury by dietary or pharmaceutical augmentation of free radical scavengers. Isocampneoside II (ICD) is an active phenylethanoid glycoside isolated from the medicinal hardwood genus Paulownia. This study was designed to explore free radical scavenging potential of ICD in different in vitro systems and its protective role in hydrogen peroxide (H₂O₂)-induced oxidative stress and apoptotic death in cultured rat pheochromocytoma (PC12) cells. The results showed ICD eliminated approximately 80.75% superoxide radical at the concentration of 0.1mg/ml and inhibited metal chelating by 22.07% at 8 mg/ml. Additionally, ICD showed a strong ability on reducing power and provided protection against oxidative protein damage induced by hydroxyl radicals. Pretreatment of PC12 cells with ICD prior to H₂O₂ exposure elevated cell viability, enhanced activity of superoxide dismutase and catalase, and decreased levels of malondialdehyde and intracellular ROS. Furthermore, ICD inhibited cell apoptosis and Bax/Bcl-2 ratio induced by H₂O₂. These findings suggested ICD may be considered as a potential antioxidant agent and should encourage for further research in neurodegenerative diseases.

N-trans-feruloyltyramine inhibits LPS-induced NO and PGE2 production in RAW 264.7 macrophages: Involvement of AP-1 and MAP kinase signalling pathways

Mitogen-activated protein kinase (MAPK) signalling pathway can regulate inflammatory and immune responses. N-trans-feruloyltyramine (FLA) is an active phenylpropanoid compound. It possesses antioxidant, antimicrobial, anti-melanogenesis, and anticancer activities. However, the precise molecular mechanisms underlying FLA modulation of cytokine expression in LPS-stimulated RAW 264.7 macrophages have not been fully investigated. In this study, we examined the mechanisms underlying the immunomodulative effects of FLA isolated from Arcangelisia gusanlung. FLA strongly suppressed mRNA expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), but not tumor necrosis factor (TNF)-α, thereby inhibiting the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Furthermore, FLA also inhibited nuclear translocation of activation protein (AP)-1, and simultaneously decreased the expression and phosphorylation of the c-Jun N-terminal kinase (JNK) protein. These results suggest that the anti-inflammatory effects of FLA might be attributed to downregulation of COX-2 and iNOS via suppression of AP-1 and the JNK signalling pathway in RAW 264.7 macrophages.

The dichloromethane fraction from Mahonia bealei (Fort.) Carr. leaves exerts an anti-inflammatory effect both in vitro and in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE Mahonia bealei has a long history of medical use in traditional Chinese medicine for the treatment of inflammatory-associated diseases. Despite numerous phytochemical and pharmacological studies, there is a lack of systematic studies to understand the cellular and molecular mechanisms of the anti-inflammatory activity of this plant. AIM OF STUDY This study aimed to evaluate the anti-inflammatory activity of the dichloromethane fraction from M. bealei leaves (MBL-CH). MATERIALS AND METHODS RAW 264.7 cells were pretreated with different concentrations of MBL-CH for 30min prior to treatment with 1μg/ml of lipopolysaccharide (LPS). The nuclear factor κB (NF-κB) pathway and subsequent production of inflammatory mediators, such as nitric oxide (NO), prostaglandin E2 (PGE2), and tumour necrosis factor (TNF)-α were investigated. Furthermore, the in vivo mouse model of LPS-induced acute lung injury (ALI) was employed to study the anti-inflammatory effects of MBL-CH. RESULTS Pre-treatment with MBL-CH significantly inhibited the LPS-stimulated secretion of NO, PGE2, and TNF-α into the culture medium, as well as the mRNA levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and TNF-α, which were associated with a reduction in the phosphorylation of IκBα, Akt, and PI3K and inhibition of the transcriptional activity of NF-κB. Furthermore, in vivo experiments revealed that MBL-CH attenuated LPS-stimulated lung inflammation in mice. CONCLUSION Taken together, our findings indicate that MBL-CH attenuates LPS-stimulated inflammatory responses in macrophages by blocking NF-κB activation through interference with activation of the PI3K/Akt pathway, providing scientific evidence that the plant can be employed in traditional remedies.

5-Methoxyl Aesculetin Abrogates Lipopolysaccharide-Induced Inflammation by Suppressing MAPK and AP-1 Pathways in RAW 264.7 Cells.

For the first time, a pale amorphous coumarin derivative, 5-methoxyl aesculetin (MOA), was isolated from the dried bark of Fraxinus rhynchophylla Hance (Oleaceae). MOA modulates cytokine expression in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages, but the precise mechanisms are still not fully understood. We determined the effects of MOA on the production of inflammatory mediators and pro-inflammatory cytokines in the LPS-induced inflammatory responses of RAW 264.7 macrophages. MOA significantly inhibited the LPS-induced production of nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), interleukin-6, and interleukin-1β. It also effectively attenuated inducible nitric oxide (NO) synthase, cyclooxygenase-2, and TNF-α mRNA expression and significantly decreased the levels of intracellular reactive oxygen species. It inhibited phosphorylation of the extracellular signal-regulated kinase (ERK1/2), thus blocking nuclear translocation of activation protein (AP)-1. In a molecular docking study, MOA was shown to target the binding site of ERK via the formation of three hydrogen bonds with two residues of the kinase, which is sufficient for the inhibition of ERK. These results suggest that the anti-inflammatory effects of MOA in RAW 264.7 macrophages derive from its ability to block both the activation of mitogen-activated protein kinases (MAPKs) and one of their downstream transcription factors, activator protein-1 (AP-1). Our observations support the need for further research into MOA as a promising therapeutic agent in inflammatory diseases.

Anti-Inflammatory Effects of Chloranthalactone B in LPS-Stimulated RAW264.7 Cells

Chloranthalactone B (CTB), a lindenane-type sesquiterpenoid, was obtained from the Chinese medicinal herb Sarcandra glabra, which is frequently used as a remedy for inflammatory diseases. However, the anti-inflammatory mechanisms of CTB have not been fully elucidated. In this study, we investigated the molecular mechanisms underlying these effects in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. CTB strongly inhibited the production of nitric oxide and pro-inflammatory mediators such as prostaglandin E2, tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and IL-6 in RAW264.7 cells stimulated with LPS. A reverse-transcription polymerase chain reaction assay and Western blot further confirmed that CTB inhibited the expression of inducible nitric oxide synthase, cyclooxygenase-2, TNF-α, and IL-1β at the transcriptional level, and decreased the luciferase activities of activator protein (AP)-1 reporter promoters. These data suggest that inhibition occurred at the transcriptional level. In addition, CTB blocked the activation of p38 mitogen-activated protein kinase (MAPK) but not c-Jun N-terminal kinase or extracellular signal-regulated kinase 1/2. Furthermore, CTB suppressed the phosphorylation of MKK3/6 by targeting the binding sites via formation of hydrogen bonds. Our findings clearly show that CTB inhibits the production of inflammatory mediators by inhibiting the AP-1 and p38 MAPK pathways. Therefore, CTB could potentially be used as an anti-inflammatory agent.

Antioxidant Activity and Protection from DNA Damage by Water Extract from Pine (Pinus densiflora) Bark

Water extract from Pinus densiflora (WPD) was investigated for its antioxidant activity and its ability to provide protection from DNA damage. A series of antioxidant assays, including a 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging assay, a reducing power assay, a metal-chelating assay, a superoxide radical scavenging assay, and a nitrite scavenging ability, as well as a DNA damage protection assay were performed. Total phenolic content was found to be 211.32 mg Tan/g WPD. The extract scavenged 50% DPPH free radical at a concentration of 21.35 μg/mL. At that same concentration, the reducing power ability of WPD was higher than that of α-tocopherol. The extract chelated 68.9% ferrous ion at the concentration of 4 mg/mL. WPD showed better nitrite scavenging effect at the lower pH. Meanwhile, WPD exhibited a strong capability for DNA damage protection at 1 mg/mL concentration. Taken together, these data suggest water extract from Pinus densiflora could be used as a suitable natural antioxidant.

Antioxidant and Nitric Oxide Production Inhibitory Activities of Scouring Rush (Equisetum hyemale L.)

Antioxidant and nitric oxide (NO) production inhibitory activities of various extracts from scouring rush (Equisetum hyemale L.) were investigated. Antioxidant assays including DPPH free radical scavenging activity, reducing power assay, metal-chelating assay, superoxide radical scavenging assay, and nitrite scavenging ability, and assays to determine total phenolic and flavonoid contents were performed. The inhibition of NO production was measured in lipopolysaccharides (LPS)-induced RAW 264.7 macrophages, and reverse transcription (RT)-PCR was used to analyse the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX-2) in RAW 264.7 macrophages. Overall, all extracts showed high phenolic content and strong DPPH radical scavenging ability. Methanol extract exhibited stronger metal-chelating activity and NO production inhibitory activity compared with other extracts. The expression of iNOS and COX-2 was obviously augmented in response to LPS. Taken together, scouring rush could be used as a suitable natural antioxidant and a source of anti-inflammatory agent.

Different Solvent Fractions of Acanthopanax senticosus Harms Exert Antioxidant and Anti-Inflammatory Activities and Inhibit the Human Kv1.3 Channel

The potential antioxidant and anti-inflammatory activities of Acanthopanax senticosus Harms were evaluated and its effect on the human Kv1.3 potassium channel was detected. The ethyl acetate fraction possessed the highest phenolic (289.19±7.43 mg tannic acid equivalents/g) and flavonoid (10.80±0.67 mg quercetin equivalents/g) contents and exhibited stronger antioxidant effects than other fractions in most of the antioxidant assays. On the other hand, the dichloromethane (CH(2)Cl(2)) fraction showed the strongest anti-inflammatory activity. The CH(2)Cl(2) fraction inhibited the expression of inducible nitric oxide synthase, cyclooxygenase-2, tumor necrosis factor-α and interleukin 1β mRNAs, and the generation of reactive oxygen species in lipopolysaccharide-induced RAW 264.7 cells. Also, the peak current was inhibited 54.8%±17% by the CH(2)Cl(2) fraction in voltage-clamp recording from Xenopus laevis oocytes. Our research demonstrated that fractions of A. senticosus have great potential to be a source of edible antioxidant and anti-inflammatory agents.

Ethanol extract of Synurus deltoides (Aiton) Nakai suppresses in vitro LPS-induced cytokine production in RAW 264.7 macrophages and in vivo acute inflammatory symptoms

Synurus deltoides (Aiton) Nakai, belonging to the Compositae family, is an edible plant widely distributed in Northeast Asia. In this study, we examined the mechanisms underlying the immunomodulative effects of the ethanol extract of S. deltoides (SDE). The SDE extract strongly down-regulated the mRNA expression of the inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and tumour necrosis factor (TNF)-α, thereby inhibiting the production of nitric oxide (NO), prostaglandin E2 (PGE2), and TNF-α in the lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Furthermore, SDE also suppressed the nuclear translocation of the activation protein (AP)-1 and the nuclear factor-κB (NF-κB), and simultaneously decreased the phosphorylation of extracellular signal-regulated protein kinases (ERK), p38, and Akt. In agreement with the in vitro observations, the orally administered SDE ameliorated the acute inflammatory symptoms in the arachidonic acid-induced ear edema and the EtOH/HCl-induced gastritis in mice. Therefore, S. deltoides have a potential anti-inflammatory capacity in vitro and in vivo, suggesting the potential therapeutic use in the inflammation-associated disorders.

Antioxidant and anti-inflammatory activities of different solvent fractions from ethanol extract of Synurus deltoides (Aiton) Nakai leaves

Fractions of Synurus deltoides (Aiton) Nakai leaves showed excellent antioxidant and anti-inflammatory effects in a series of antioxidant and anti-inflammatory assays including total phenolic and flavonoid contents determination assay, DPPH free radical scavenging assay, reducing power assay, superoxide radical scavenging assay, nitrite scavenging assay, total antioxidant assay, DNA damage protection assay, MTT assay, nitric oxide (NO) production inhibition assay, and reverse transcription (RT)-PCR assay. The ethyl acetate fraction exhibited stronger antioxidant effects than other fractions in most of antioxidant assays such as DPPH assay, reducing power assay, superoxide radical scavenging assay, and nitrite scavenging assay. However, the dichloromethane fraction showed the strongest total antioxidant activity and NO production inhibitory activity. It was demonstrated that S. deltoides was valuable to be researched farther and application and fractions of S. deltoides had great potential to be a source of edible antioxidant and anti-inflammatory agents.